This invention relates generally to saw blades and, more specifically, to an improved blade for a surgical saw.
A conventional blade for a surgical saw has a relatively flat, elongated body which is attached at one end to a powered drive source. A row of teeth is typically formed on an outwardly facing edge surface of the end of the blade opposite the drive source. The drive source imparts a reciprocating motion to the blade which is used to effect the cutting of relatively hard body tissues. The angular excursion of the reciprocating blade is severely limited to prevent the accidental cutting of soft tissues which tend to vibrate or move with the blade upon contact with the saw blade teeth.
A conventional saw tooth pattern typically incorporates a gullet (i.e., the space between adjacent teeth) which is defined by surfaces which lie in planes generally perpendicular to the flat surfaces of the blade. This pattern is satisfactory in applications where the teeth exit the cut and deposit cuttings, stored in gullets, outside the cut. In the case of a surgical saw application, the teeth typically do not leave the cut and, accordingly, cuttings tend to build up in the gullets and retard cutting. The substantially perpendicular surfaces which define the gullets in a conventional blade effectively trap the cuttings between the sharp surfaces of the teeth.
An object of the present invention is to provide an improved tooth design for a surgical saw which overcomes problems associated with conventional saw tooth designs.
Another object of the present invention is to provide an improved tooth design for a surgical saw in which relatively large spaces are provided between adjacent teeth, and in which these spaces are defined by surfaces which lie in planes which are non-perpendicular to the flat surfaces of the blade.
These and other objects of the invention are attained in a blade for a surgical saw which comprises an elongate body having first and second substantially flat surfaces, and having a proximal end and a distal end. A plurality of teeth are formed on an outwardly facing edge surface of the distal end of the blade. The spaces between adjacent teeth are defined by surfaces which lie in planes which are non-perpendicular to the first and second substantially flat surfaces whereby the cuttings generated by the teeth are guided laterally toward the flat surfaces of the blade and outwardly toward the proximal end of the blade as the blade advances in a cut.
The plurality of teeth formed on the outwardly facing edge surface of the end of the blade preferably include a first set of teeth spaced apart in a first row and a second set of teeth spaced apart in a second row. Each tooth of the first set has a point which lies in a first cutting plane which extends in parallel with, and lies adjacent a first side of, a plane which extends longitudinally through the center of the body. Each tooth of the second set has a point which lies in a second cutting plane which extends in parallel with, and lies adjacent a second side of, the plane which extends longitudinally through the center of the body. The plurality of teeth are disposed in alternating relation such that each tooth in the first set is disposed between two teeth of the second set, and vice versa.
In one embodiment of the blade, at least one of the surfaces which define the spaces between adjacent teeth intersects the longitudinal plane which extends through the center of the blade, and the substantially parallel flat surfaces of the blade, at an angle of approximately 45.degree. . In another embodiment, each space between adjacent teeth is defined by at least two surfaces which lie in such planes, and which intersect each other at an angle of approximately 90.degree..
In one embodiment of the invention, the outwardly facing edge of the blade comprises a plurality of alternating surfaces which lie in alternately intersecting planes. These planes intersect the longitudinal plane which extends through the center of the blade at substantially equal acute angles. Each of the alternating teeth of the blade is formed on a respective one of these alternating surfaces. Each of these teeth have a triangular cross-section, and comprises a base, which lies in the same plane as the surface upon which the tooth is formed, and two side surfaces extending upwardly from the base and intersecting above the base to form the point of the tooth. The base of the triangular tooth has a width which only partly covers the coplanar surface upon which the tooth is formed. The portions of the surface on either side of the base of the tooth form "back" surfaces of the space between adjacent teeth (i.e., the gullet). Those surfaces are aligned to "face" the direction of the cut, but are angled so as to guide cuttings produced by the blade outwardly and backwardly toward the proximal end of the blade. Each of the side surfaces of the tooth is shaped as a parallelogram which shares a common side to form a knife-like cutting edge extending from the point backwardly toward the proximal end of the blade.
In one embodiment of the blade, the first and second cutting planes are substantially parallel to, and are spaced outwardly from, the first and second substantially flat surfaces of the blade. This embodiment increases the width of the kerf to provide more room for cuttings to be deposited between the body of the blade and the cut surfaces.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.